prior to和before都有“在......之前”的含义，二者后面通常加时间，但before可以做连词，后面接句子，prior to却不可以，另外，就prior 而言，常见的表达还有prior written notice(事先书面通知)，一般来讲，在合同中，prior比before更正式。
1
The obligation of the Investor to make the Investment at Completion shall be conditional upon the fulfillment on or prior to the Completion Date, or waiver by the Investor in writing, of the following conditions:
投资方在交割时的投资义务应当以下列条件在交割日或交割日之前得以满足或者由投资方书面豁免作为前提：
2
The parties hereto shall use all reasonable endeavours to fulfil or procure the fulfillment of the Conditions Precedent set out in Clause 3(A) on or before the Long Stop Date.
各方当事人应当尽其一切合理努力在最后截止日期或最后截止日期之前满足第3(A)条规定的先决条件或者促使前述先决条件得以满足。